Introduction The development of civilian electric traffic products is the largest market for batteries in the future. Whether the market can achieve rapid and steady development depends critically on the operating costs of electric transportation products. Among them, there are several technical indicators surrounding the battery, such as the unit's energy storage index, cycle life, whether the charging after discharge is safe and convenient, and the adaptability of changes in the ambient temperature, etc., which are the core of the operating costs. Breakthrough of any of the above technical indicators will make the battery a solid step forward in the application of electric traffic products.
1 Battery and Charging Technology For the lead-acid, nickel-cadmium, and nickel-metal hydride electrolytes that use water as the solvent, there are several generations of chemical power workers around the world that are safe, convenient, long-lived, and maintenance-free. With the efforts, the theoretical mechanism of the "internal oxygen cycle" was finally discovered from a large number of experiments, so that all the charge and discharge reactions of the three types of batteries can be safely performed in a well-designed sealed container with valve control. That is, during the charging and overcharging of the battery, the oxygen that has been deposited on the positive electrode reaches the negative electrode and can be completely absorbed and reduced by the negative electrode. The relationship is i (O2 precipitation) = i (O2 reduction), and thus, the battery is charged and discharged during a long period of time. In the process, the loss of water in the electrolyte will not be caused, so as to ensure the cycle life of the battery and the safety of the charging. This theory is clearly correct when it is possible to accurately control the charging current and other charging side reactions while making the influence of environmental factors smaller. Unfortunately, this correct theory is only a researcher from chemical power sources and has not been truly understood and valued by circuit workers for a long time. As a result, the development of battery technology leads the development of charging technology. As a result, today when we actually use the battery, we often see that the battery does not reach the designed service life, and the performance is degraded or even scrapped. We have spent 8 years researching the traditional battery constant current and constant voltage charging technology, as well as the subsection constant current, current limiting constant voltage and other charging technologies extended by the development of this technology. The following is our understanding of traditional charging technology.
The constant-current charging method, as the name implies, means that after the battery is discharged, during the process of charging and recovering the capacity, the charger is required to charge the battery at a certain output current according to the different A·h number of the battery. The current flows from the battery. From the start of charging to the end of charging, it is always constant.
The constant voltage charging method, as the name implies, means that after the battery is discharged, during the process of charging and restoring capacity, the charger is required to press different types of batteries to charge the battery with a certain output voltage, and the voltage is charged from the battery. From the beginning to the end of charging, it is always constant.
It is the most widely used and most commonly used at home and abroad. The lead-acid battery with the most profound research and analysis is taken as an example. Take a look at Figure 1, which is often seen and used in the study of valve-regulated lead-acid battery technology. Here we have to explain is that this picture is the experts out of the impact of daily environmental temperature changes on the battery charging process, with an improved constant voltage current limiting method to the battery charge obtained. Because it is a constant voltage and current-limited charging method, it represents the I-line of the current change, and there is a small segment in the initial segment that is the current limit value. The initial section of the V line that represents the voltage is a very steep rise line, and more precisely because the charger's current limiting effect should be the voltage drop line.
In FIG. 1 , the left longitudinal axis represents the battery charging voltage and the horizontal axis represents time. The I line represents the current change curve of the battery's ability to receive electricity at different times during charging. The V line represents the highest level of safety that can be accepted at various times during battery charging. The voltage is also the constant voltage output line of the designed charger, and the C line represents the recovery curve of the performance of the battery during the charging process over time.
From the I curve, it can be clearly seen that the current capacity of the battery at different times during the charging process. Obviously, on the time axis, the battery current acceptance curve I is a very variable nonlinear curve, the battery's current acceptance capability is completely different at each moment, then the current at this moment in the curve is used as the battery constant current charging, The battery can be made safe and it can fill the battery for a limited period of time that people can accept. Including the constant-current charging method with a limited number of improved constant-current methods, no matter how we look at it, we find it difficult to achieve. The more difficult is that the battery depth of discharge is not the same for each use, the ambient temperature is not the same, the old and new degree is not the same, if each charge with the same current and time to charge, resulting in battery damage is not Reversal.
Looking at the constant voltage charging method again, we can see from the V line that the output voltage of the charger is always the highest allowable voltage that the charger designer thinks that the battery is safely powered. Below this voltage, it will not be able to make the battery full. Is voltage really safe? The relevant information clearly tells us that during the charging process, the charging voltage of the single cell battery is 100mV higher than the real-time voltage of the battery itself, and the charging current through the battery is more than 10 times greater than the maximum safe receiving current of the battery. Before charging, the battery is usually discharged after the battery is discharged. At this time, the battery is definitely at the lowest voltage. Such as monomer lead-acid batteries, after discharge is generally 1.8 ~ 2.0V, and when the charging voltage is constant at 2.25 ~ 2.4V, it can be seen that the charger output voltage and battery voltage difference is much greater than 100mV.
This kind of constant voltage charging, through the battery's charging current will be the battery's maximum safety current of several dozen times, if the charger's output power and capacity is large enough, it will inevitably cause the damage of the battery, if the capacity of the charger is not enough, then Will definitely cause the charger's overload burned. After the improved constant voltage current limiting charging method, in order to protect the battery and the charger from damage, the charging efficiency is reduced, the loss is increased, and the charging time is prolonged. This is the start of the constant voltage charging V line. From the time period to the final stage of the V line, since most chargers do not have the ability to track and compensate for changes in the ambient temperature, the charger still retains the maximum current output capability at this time. If you do not turn off the charging power supply in time, it is very easy to cause damage to the battery in the change of the ambient temperature. At this point, we can see that the important reasons for the early performance degradation and loss of capacity caused by the use of valve-regulated batteries are mostly due to the backwardness of traditional battery charging technologies and the inadequacy of process control.
2 The new charging mode analyzes the problems existing in the traditional battery charging technology. After a long period of thinking and experimentation, we have proposed a new mode of “Battery Natural Balanced Charging Methodâ€. The charging process is as follows.
In Figure 2, there are two power supplies EA and EB. When the power supply EA and the power supply EB are at the same ambient temperature, the positive electrode and the positive electrode are connected, and the negative electrode and the negative electrode are connected. In the closed loop formed by them, the following relationship exists. If the EA power supply is higher than the power supply EB, the A power supply will supply the EA-EB=ΔE voltage to the B power supply, which will provide a Δi current according to the magnitude of ΔE, so that when the power supply EB rises to the voltage of the power supply EA completely, (in the battery In the performance of the battery terminal voltage rise and increase the amount of charge storage). The power supply EA will stop supplying current to the power supply EB, that is, EA=EB, ΔE=0, and Δi=0.
In the above description, we replaced the power source EB with a charged battery, and found out that the battery voltage corresponds to different depth of discharge and ambient temperature. The A power supply voltage EA is carefully designed to be able to automatically adjust the output voltage and current power according to the battery charge balance requirements under different ambient temperatures. Corresponding connection, in the case of perfect idealization, the power supply EA can be based on the battery in any At ambient temperature, an acceptable safety current is charged to the battery. After the battery is fully charged, ΔE=0 and Δi=0. The A power supply will not consume power. After that, the A power supply EA changes only with the ambient temperature. Charge the battery to provide tracking balance compensation. The entire process of battery charging is completely automated. Therefore, we call it the natural balance method.
The idealization of this method is that after the battery is fully charged, the A power EA has no power to supply the battery EB. The actual situation has been experimentally verified to be slightly different from the ideal situation proposed above. That is, after the battery A is fully charged, the A power supply maintains a small but balanced battery pack due to the battery leakage and internal oxygen cycle requirements. Very useful current, due to the existence of this characteristic, almost makes this charging technology closer to perfection.
1 Battery and Charging Technology For the lead-acid, nickel-cadmium, and nickel-metal hydride electrolytes that use water as the solvent, there are several generations of chemical power workers around the world that are safe, convenient, long-lived, and maintenance-free. With the efforts, the theoretical mechanism of the "internal oxygen cycle" was finally discovered from a large number of experiments, so that all the charge and discharge reactions of the three types of batteries can be safely performed in a well-designed sealed container with valve control. That is, during the charging and overcharging of the battery, the oxygen that has been deposited on the positive electrode reaches the negative electrode and can be completely absorbed and reduced by the negative electrode. The relationship is i (O2 precipitation) = i (O2 reduction), and thus, the battery is charged and discharged during a long period of time. In the process, the loss of water in the electrolyte will not be caused, so as to ensure the cycle life of the battery and the safety of the charging. This theory is clearly correct when it is possible to accurately control the charging current and other charging side reactions while making the influence of environmental factors smaller. Unfortunately, this correct theory is only a researcher from chemical power sources and has not been truly understood and valued by circuit workers for a long time. As a result, the development of battery technology leads the development of charging technology. As a result, today when we actually use the battery, we often see that the battery does not reach the designed service life, and the performance is degraded or even scrapped. We have spent 8 years researching the traditional battery constant current and constant voltage charging technology, as well as the subsection constant current, current limiting constant voltage and other charging technologies extended by the development of this technology. The following is our understanding of traditional charging technology.
The constant-current charging method, as the name implies, means that after the battery is discharged, during the process of charging and recovering the capacity, the charger is required to charge the battery at a certain output current according to the different A·h number of the battery. The current flows from the battery. From the start of charging to the end of charging, it is always constant.
The constant voltage charging method, as the name implies, means that after the battery is discharged, during the process of charging and restoring capacity, the charger is required to press different types of batteries to charge the battery with a certain output voltage, and the voltage is charged from the battery. From the beginning to the end of charging, it is always constant.
It is the most widely used and most commonly used at home and abroad. The lead-acid battery with the most profound research and analysis is taken as an example. Take a look at Figure 1, which is often seen and used in the study of valve-regulated lead-acid battery technology. Here we have to explain is that this picture is the experts out of the impact of daily environmental temperature changes on the battery charging process, with an improved constant voltage current limiting method to the battery charge obtained. Because it is a constant voltage and current-limited charging method, it represents the I-line of the current change, and there is a small segment in the initial segment that is the current limit value. The initial section of the V line that represents the voltage is a very steep rise line, and more precisely because the charger's current limiting effect should be the voltage drop line.
In FIG. 1 , the left longitudinal axis represents the battery charging voltage and the horizontal axis represents time. The I line represents the current change curve of the battery's ability to receive electricity at different times during charging. The V line represents the highest level of safety that can be accepted at various times during battery charging. The voltage is also the constant voltage output line of the designed charger, and the C line represents the recovery curve of the performance of the battery during the charging process over time.
From the I curve, it can be clearly seen that the current capacity of the battery at different times during the charging process. Obviously, on the time axis, the battery current acceptance curve I is a very variable nonlinear curve, the battery's current acceptance capability is completely different at each moment, then the current at this moment in the curve is used as the battery constant current charging, The battery can be made safe and it can fill the battery for a limited period of time that people can accept. Including the constant-current charging method with a limited number of improved constant-current methods, no matter how we look at it, we find it difficult to achieve. The more difficult is that the battery depth of discharge is not the same for each use, the ambient temperature is not the same, the old and new degree is not the same, if each charge with the same current and time to charge, resulting in battery damage is not Reversal.
Looking at the constant voltage charging method again, we can see from the V line that the output voltage of the charger is always the highest allowable voltage that the charger designer thinks that the battery is safely powered. Below this voltage, it will not be able to make the battery full. Is voltage really safe? The relevant information clearly tells us that during the charging process, the charging voltage of the single cell battery is 100mV higher than the real-time voltage of the battery itself, and the charging current through the battery is more than 10 times greater than the maximum safe receiving current of the battery. Before charging, the battery is usually discharged after the battery is discharged. At this time, the battery is definitely at the lowest voltage. Such as monomer lead-acid batteries, after discharge is generally 1.8 ~ 2.0V, and when the charging voltage is constant at 2.25 ~ 2.4V, it can be seen that the charger output voltage and battery voltage difference is much greater than 100mV.
This kind of constant voltage charging, through the battery's charging current will be the battery's maximum safety current of several dozen times, if the charger's output power and capacity is large enough, it will inevitably cause the damage of the battery, if the capacity of the charger is not enough, then Will definitely cause the charger's overload burned. After the improved constant voltage current limiting charging method, in order to protect the battery and the charger from damage, the charging efficiency is reduced, the loss is increased, and the charging time is prolonged. This is the start of the constant voltage charging V line. From the time period to the final stage of the V line, since most chargers do not have the ability to track and compensate for changes in the ambient temperature, the charger still retains the maximum current output capability at this time. If you do not turn off the charging power supply in time, it is very easy to cause damage to the battery in the change of the ambient temperature. At this point, we can see that the important reasons for the early performance degradation and loss of capacity caused by the use of valve-regulated batteries are mostly due to the backwardness of traditional battery charging technologies and the inadequacy of process control.
2 The new charging mode analyzes the problems existing in the traditional battery charging technology. After a long period of thinking and experimentation, we have proposed a new mode of “Battery Natural Balanced Charging Methodâ€. The charging process is as follows.
In Figure 2, there are two power supplies EA and EB. When the power supply EA and the power supply EB are at the same ambient temperature, the positive electrode and the positive electrode are connected, and the negative electrode and the negative electrode are connected. In the closed loop formed by them, the following relationship exists. If the EA power supply is higher than the power supply EB, the A power supply will supply the EA-EB=ΔE voltage to the B power supply, which will provide a Δi current according to the magnitude of ΔE, so that when the power supply EB rises to the voltage of the power supply EA completely, (in the battery In the performance of the battery terminal voltage rise and increase the amount of charge storage). The power supply EA will stop supplying current to the power supply EB, that is, EA=EB, ΔE=0, and Δi=0.
In the above description, we replaced the power source EB with a charged battery, and found out that the battery voltage corresponds to different depth of discharge and ambient temperature. The A power supply voltage EA is carefully designed to be able to automatically adjust the output voltage and current power according to the battery charge balance requirements under different ambient temperatures. Corresponding connection, in the case of perfect idealization, the power supply EA can be based on the battery in any At ambient temperature, an acceptable safety current is charged to the battery. After the battery is fully charged, ΔE=0 and Δi=0. The A power supply will not consume power. After that, the A power supply EA changes only with the ambient temperature. Charge the battery to provide tracking balance compensation. The entire process of battery charging is completely automated. Therefore, we call it the natural balance method.
The idealization of this method is that after the battery is fully charged, the A power EA has no power to supply the battery EB. The actual situation has been experimentally verified to be slightly different from the ideal situation proposed above. That is, after the battery A is fully charged, the A power supply maintains a small but balanced battery pack due to the battery leakage and internal oxygen cycle requirements. Very useful current, due to the existence of this characteristic, almost makes this charging technology closer to perfection.
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